1. Field of the Invention
The invention relates to a polypropylene-based resin composition and a molded product thereof.
2. Background Art
Due to increasing awareness of global environmental issues in recent years, generation of hydrogen chloride gas during combustion of poly(vinyl chloride) materials (hereinafter referred to as “PVC materials”) is acknowledged as a problem. Development and use of materials giving due consideration to the global environmental is strongly desired.
In view of this situation, replacing known PVC materials with olefin-based materials as an environment-conscious material is being investigated.
As known olefin-based materials that can be substituted for the PVC materials, ethylene-based resins such as EEA (ethylene-ethyl acrylate copolymer) and EVA (ethylene-vinyl acetate copolymer) are used as basic materials.
These materials, however, have a problem of insufficient heat resistance, because a major component is a polyethylene resin. In the tape application, for example, a high drying temperature cannot be used after application of an adhesive to a film after forming, leading to a poor productivity. In addition, when the tape is used as an adhesive tape for vehicle mounting, the tape may be peeled away or frizzled due to insufficient heat resistance. Thus, insufficient heat resistance has been a problem.
If a known ethylene-based material is simply replaced with polypropylene(PP)-based material excelling in heat resistance, for example, in order to solve this problem, not only superior characteristics as an adhesive film possessed by known PVC materials such as texture and hand-cutting properties are impaired, but also calendar molding frequently used in the PVC material forming processes may not be applied with difficulty (see Japanese Patent Applications Laid-open No. 2002-128975 and No. 2002-167476).
The invention has been completed in view of the above-described situation and has an object of providing a polypropylene-based resin composition excelling in calendar moldability and capable of producing a molded product exhibiting excellent heat resistance and having good texture and hand-cutting properties, and a molded product made from the composition.
As a result of extensive studies to achieve this object, the inventors has found a combined use of a polypropylene-based soft resin, a homopolypropylene, and a propylene-ethylene random copolymer having specific properties and specific structures as resin components. This finding has led to the completion of the invention.